1. Field of the Invention
The present invention relates to an ophthalmologic diagnostic apparatus for examining an eye fundus in an ophthalmologic office or the like.
2. Description of Related Art
An eye fundus blood flow meter, a laser flare cell meter, and the like have been known as ophthalmologic diagnostic apparatuses for irradiating laser light into an eye to measure a characteristic of an eye to be examined. The eye fundus blood flow meter is used to measure a blood flow of a blood vessel of an eye fundus which can be directly observed in a noninvasive manner. Various eye fundus blood flow meters for conducting laser light irradiation and utilizing a Doppler measurement theory or a speckle phenomenon have been devised, which are now being anticipated for use for a wide range of applications.
In the ophthalmologic diagnostic apparatus as described above, for the safety of an eye of a person to be examined, a maximum permissible exposure (MPE) has been defined by American National Standards Institute (ANSI) as the maximum permissible laser energy of laser light which may be irradiated.
In the conventional ophthalmologic diagnostic apparatus as described above, an operator himself measures an irradiation time of measurement laser light to an eye fundus to perform irradiation operation such that irradiation energy does not exceed the MPE, thus causing an inconvenience to the operator.
In order to solve such a problem, an apparatus for conducting time integration of outputs of measurement laser light for each person to be examined and calculating irradiation energy to display a message, to give an alarm, to stop laser light irradiation, or the like so that irradiation energy of the measurement laser light does not exceed the MPE is proposed in Japanese Patent Application Laid-Open No. 9-131320.
Also, an apparatus for detecting the amount of light illuminated to an eye of a person, integrating it, comparing the integrated amount of light with the safety permissible cumulative amount of light that may be illuminated to an eye of a person, and controlling the amount of light to be illuminated in order to protect an eye of a person when the integrated amount of light exceeds the safety permissible cumulative amount of light is proposed in Japanese Patent No. 2685239. According to this invention, the safety permissible cumulative amount of light that may be illuminated to an eye of a person are controlled for each of left and right eyes.
However, in an apparatus for irradiating laser light to an eye to be examined, such as the eye fundus blood flow meter, irradiation light is irradiated not over the entire eye fundus but per each predetermined area. In view of this, it is desirable that laser irradiation energies are controlled for each of left and right eyes to be examined and for each measurement position.
When the laser irradiation energies are calculated for each person to be examined and for each of left and right eyes so that they do not exceed the MPE as in the above conventional example, there is a case where the number of measurements that may be actually performed is limited for the safety of a person to be examined, when using an apparatus for irradiating laser illumination light to a local region such as a blood vessel of an eye to be examined, such as the eye fundus blood flow meter, to conduct a measurement.
The present invention has been devised to provide improvements over the above-mentioned conventional art. Specifically, an object of the invention is to provide an ophthalmologic apparatus in which the number of measuring light irradiation can be increased while securing the safety of a person to be examined.
In order to achieve the above-mentioned object, there is provided an ophthalmologic apparatus comprising an irradiation optical system for irradiating a light beam to an eye to be examined, a timer for measuring an irradiating time of the light beam; and a controller which controls the irradiating time, by calculating integrated irradiation energy for each of a plurality of positions on the eye to be examined based on the irradiating time measured by the timer.
Further, according to the present invention, the ophthalmologic apparatus may further comprise a sensor for monitoring the light beam output, and the controller calculates the integrated irradiation energy based on an output of the sensor and the irradiating time measured by the timer.
Further, according to the present invention, the apparatus may further comprise means for discriminating between left and right eyes to be examined, and the controller controls the position based on a result of the above discrimination.
Further, according to the present invention, the apparatus may further include means for detecting an irradiation position of a light beam to an eye fundus and the controller can specify the above-mentioned position based on the discrimination between the left and right eyes and the inputted irradiation position.
Further, according to the present invention, the controller can set a predetermined region as the above-mentioned position and control the sum of irradiation energies by corresponding to measurement positions present in the region in correspondence with the position.
Further, according to the present invention, the apparatus may further comprise a display unit for displaying the integrated irradiation energy at each of the above-mentioned positions. The display unit may further display the proportion of the integrated irradiation energy to a predetermined value.
Further, the present invention may be constructed such that when a value of the integrated irradiation energy exceeds a predetermined value or larger, an alarm is given or irradiation of the light beam is restricted.